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Unidirectional Flushing

​​Charlotte Water will be clearing mineral deposits (sediment) from water pipes by flushing water through fire hydrants during April, May, June, and July. The mineral deposits in the pipes are only dislodged when the water is flowing at very high speeds. It has not impacted water quality but may have impacted water pressures and pipe capacity.

Water quality sampling stations (green boxes) may be installed in the neighborhood so staff can test the water before and after flushing hydrants.

Flushing will be conducted after 8:00 a.m. and before 5:00 p.m. Monday through Friday for most streets. Flushing will have minimal impacts to customers. If you see hydrant flushing crews working in the area, please drive carefully and treat them like any other road construction crew.

Discolored Water is Possible

Customers in the immediate vicinity of flushing may notice temporarily discolored water and lower than normal water pressure. The discoloration does not pose a health risk. However, avoid using tap water or running the washing machine or dishwasher until flushing is complete.

If you experience some discoloration in your water from nearby flushing, run the cold water at one tap for 5 minutes to see if it clears. If it does not clear wait an hour and try again. When the water runs clear, flush any taps where discolored water was present. If not clear after one hour, call 311 to report issues

Unidirectional Flushing FAQs​

​Unidirectional flushing is used to improve and maintain our high-quality drinking water. Sediments and mineral deposits in the pipes can discolor drinking water. The high-speed water flows used in unidirectional flushing is an efficient and cost-effective way to remove sediments and deposits from the pipes and prevent potential water quality issues.

​Drinking water pipes need to be flushed out to improve water quality. Over time, very fine sediment from mineral deposits and organic matter settle out of the water and accumulate in the bottom of the pipes. While the sediments are generally harmless, they can make the disinfectant in the water less effective. Additionally, sudden changes in the flow of water can disturb these sediments resulting in cloudy, discolored water.​

Charlotte Water uses three techniques to clean and maintain the drinking water system: spot flushing, autoflushing, and unidirectional flushing.

Spot flushing is used to address discolored water issues. This includes when drinking water is discolored due to a disturbance in the system such as construction or other hydrant activity. Crews open fire hydrants to flush this water out of the system and bring fresh water into the pipes.

Autoflushing is similar to spot flushing and is used to maintain water quality by reducing water age in the distribution system. This type of flushing uses an automatic flushing device, called an autoflusher, which is connected to hydrants and programmed to flush water at certain time intervals and flow rates. Using an autoflusher reduces the amount of staff time needed to maintain consistently better water quality at a certain location in the distribution system while using water in a more efficient manner.

Unidirectional flushing is not used in response to a specific water quality issue but instead is used as routine maintenance to prevent problems from arising. The goal of unidirectional flushing is to clean the insides of the water delivery pipes. Cleaning the pipes removes sediment that builds up in the pipes. This reduces the potential for water quality problems. Unidirectional flushing works by forcing water in the pipes to flow at much higher speeds than normal. Flushing crews first open and close valves to isolate sections of pipe, and then the water and any mineral sediments in the pipes are flushed out through an open fire hydrant.

The sediment from mineral deposits in the pipes is only dislodged when the water is flowing at very high speeds. It has not impacted water quality but may have impacted water pressures and pipe capacity.

Unidirectional flushing will have minimal impacts to customers. If you see hydrant flushing crews working in the area, please drive carefully and treat them like any other road construction crew.

Customers in the immediate vicinity of flushing may notice temporarily discolored water and lower than normal water pressure. The discoloration does not pose a health risk. However, avoid using tap water or running the washing machine or dishwasher until flushing is complete.

If you experience some discoloration in your water from nearby flushing, run the cold water at one tap for 5 minutes to see if it clears. If it does not clear wait an hour and try again. When the water runs clear, flush any taps where discolored water was present. If not clear after one hour, call 311 to report issues.